The present invention relates to a semiconductor device and a method of manufacturing the same, and particularly to a semiconductor device including a magnetic resistor element and a method of manufacturing the same.
As a form of a semiconductor device, there is a Magnetic Random Access Memory (MRAM) to which a magnetic resistor element called a Magnetic Tunnel Junction (MTJ) is applied. In the MRAM, the magnetic resistor elements are formed in an array configuration. In each of the magnetic resistor elements, two magnetic layers are stacked with a tunnel insulating film interposed therebetween. According to whether magnetizations in the two magnetic layers are oriented into the same directions or into opposite directions, the resistance value of the magnetic resistor element varies. In the MRAM, the difference in resistance value is used as information. That is, magnetization orientations in the two magnetic layers serve as information corresponding to “0” and “1”.
A description will be given to the outline of a method of manufacturing the MRAM. A conductive layer and digit lines are formed, and an interlayer insulating film is formed so as to cover the conductive layer and the digit lines. Then, via holes are formed in the interlayer insulating film to expose the conductive layer, and plugs are formed in the respective via holes. Then, a layer serving as lead-out electrodes is formed over the interlayer insulating film, and predetermined layers each forming magnetic resistor elements are formed thereover. Then, predetermined photoengraving and etching are performed to form the lead-out electrodes and the magnetic resistor elements which are electrically coupled to the conductive layer.
Then, an interlayer insulating film is formed so as to cover the magnetic resistor elements. The interlayer insulating film is subjected to a polishing process, and thereby planarized. Then, predetermined wire grooves are formed in the interlayer insulating film so as to expose the surfaces of the magnetic resistor elements. Then, bit lines are formed in the wire grooves. In this manner, the main portion of the semiconductor device including the magnetic resistor elements electrically coupled to the bit lines and to the conductive layer is formed. The magnetization orientation in each of the magnetic resistor elements is changed by a magnetic field produced by allowing predetermined currents to flow in the corresponding bit line and the corresponding digit line. Examples of a document disclosing such a semiconductor device including magnetic resistor elements include Patent Document 1 and Patent Document 2.